Text a giant sign

Here's a business idea for both mobile phone companies and people who operate those giant digital signs in public places (such as malls and the Times Square jumbotron.)

Let people text a message to the sign for a lucrative but affordable fee. It would then display ASAP, though possibly a human would have to check for "offensive" messages, whatever that means. You could see people putting up love notes to their valentines as they both go by the sign, rivals having battles and debates in their messages etc. Could be both entertaining and lucrative. The texted billboards (or from a web form with graphics) would contain a bar with the texting number or URL to enter your own. If it were cheap enough you might see crowds stopping to enjoy the battles on the jumbotron.

Several years ago in NYC, the Joe Boxer Billboard had a large scrolling sign that displayed email that was sent to the address on the static part of the sign.

It was free, but mostly inane and no converstations formed. Part of the issue was the obvious "man in the middle" validating the content. I spent fifteen minutes watching the scroll after calling a friend to have them send a message and it never showed, and I saw the same set of message go past at least 3 times.

Actually, Sony Ericsson attempted the same thing this year at WTA Tour (tennis). The thing I am wondering though is what kinda content would people stop and gander at for a few minutes? A debate? a haiku? Would there be famous/pro bigtxters like there are famous/pro bloggers?